1. Field of the Invention
The invention relates to a reactor and a manufacturing method of the reactor. The reactor is a passive element using a coil, and is also referred to as an “inductor”.
2. Description of Related Art
A reactor includes a magnetic core, and a coil wound around the core. There is a type of a reactor that includes a bobbin between a coil and a core. In many cases, a reactor is often covered by a resin for the purpose of insulation and protection from physical contact with other devices (for example, Japanese Utility Model Application Publication No. 5-066950 (JP 5-066950 U), Japanese Patent Application Publication No. 2011-249427 (JP 2011-249427 A), Japanese Patent Application Publication No. 2009-24222 (JP 2009-246222 A)).
In a motor drive system of an electric vehicle including a hybrid vehicle, a reactor is sometimes used for a circuit of a voltage converter and so on. Since large current flows through a reactor for an electric vehicle, a calorific value is large. JP 5-066950 U discloses a reactor in which a coil is entirely covered by a resin. When the coil is entirely covered by a resin as stated above, it is difficult to dissipate heat from a coil if a calorific value is high. Therefore, a technology is proposed, in which a part of a coil is exposed in a resin cover and the exposed part promotes heat dissipation from the coil (for example, JP 2011-249427 A, and JP 2009-246222 A).
In the technology described in JP 2011-249427 A, one surface of a metallic block with high thermal conductivity abuts on a part where a coil is exposed. Also, the other surface of the metallic block abuts on a housing. By doing so, heat of the coil is diffused to the housing through the metallic block. In the technology described in JP 2009-246222 A, about a half of a coil is covered by a resin, and the other half is exposed. Air is sent to the exposed part to cool the coil.